title: Orbital dilution effect in ferrimagnetic Fe(1-x)Mn(x)Cr(2)O(4): competition between anharmonic lattice potential and spin-orbit coupling.
abstract: Magnetic and structural phase diagram in a spinel-type solid solution system Fe(1-x)Mn(x)Cr(2)O(4) has been investigated. The cubic-to-tetragonal transition temperature T(s 1) is gradually reduced by the substitution of Mn(2+) (3d(5)) for Jahn-Teller-active Fe(2+) (3d(6)) ions, implying the long-range nature of the ferroic interaction between orbitals. In the paramagnetic tetragonal phase for x < 0.5, the c parameter is shorter than a because of the anharmonicity of the elastic energy. The crystal structure further changes to orthorhombic at around the ferrimagnetic transition temperature T(N 1). T(s 1) and T(N 1) meet at x = 0.5, and Mn substitution of more than 0.5 gives rise to another tetragonal phase with a < c. The systematic change in crystal structure is discussed in terms of competition between the anharmonic lattice potential and the intra-atomic spin-orbit interaction at Fe(2+).
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohtani
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: N
authors.initials: N
authors.lastname: Abe
authors.forename: K
authors.initials: K
authors.lastname: Taniguchi
authors.forename: H
authors.initials: H
authors.lastname: Sagayama
authors.forename: T
authors.initials: T
authors.lastname: Arima
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Noda